Control and power module for driving a brushless motor in a power tool

ABSTRACT

A power tool is provided including a tool housing; at least one battery receptacle accommodated on the tool housing, the battery receptacle being adapted to receive a battery pack having a maximum voltage of at least 60 volts; and a brushless DC (BLDC) motor disposed within the tool housing, the motor including a stator assembly and a rotor assembly rotatably disposed within the stator assembly. A motor control and power module is disposed in close proximity to the motor, including a power switch circuit electrically coupled to the motor and a first controller configured to control a switching operation of the power switch circuit for supply of power from the battery pack to the motor. A battery management control module is disposed in close proximity to the battery receptacle, including a second controller distinct from the first controller, the second controller configured to manage an operation of the battery pack.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/248,798 filed Oct. 30, 2015, and U.S. Provisional Application No.62/358,732 filed Jul. 6, 2016, both of which are incorporated herein byreference in their entireties.

FIELD

This disclosure relates to high-power power tools having brushlessmotors, and in particular to a brushless motor and associated controland power module for a high-power power tool.

BACKGROUND

Cordless power tools provide many advantages to traditional corded powertools. In particular, cordless tools provide unmatched convenience andportability. An operator can use a cordless power tool anywhere andanytime, regardless of the availability of a power supply. In addition,cordless power tools provide increased safety and reliability becausethere is no cumbersome cord to maneuver around while working on the job,and no risk of accidently cutting a cord in a hazardous work area.

However, conventional cordless power tools still have theirdisadvantages. Typically, cordless power tools provide far less power ascompared to their corded counterparts. Today, operators desire powertools that provide the same benefits of convenience and portability,while also providing similar performance as corded power tools.

Brushless DC (BLDC) motors have been used in recent years in variouscordless power tools. While BLDC motors provide many advantages overuniversal and permanent magnet DC motors, challenges exist inincorporating BLDC motors into many power tools depending on powerrequirements and specific applications of tool. The power componentsneeded for driving the BLDC motors in high power applications haveconventionally generated too much heat, making BLDC motors unfeasiblefor high-power power tools. Furthermore, high power applicationstypically require larger motors. As power tools have become moreergonomically compact, it has become more desireable to reduce the sizeof the motor while providing the required power output.

SUMMARY

According to an aspect of the invention, a power tool is providedincluding a tool housing; at least one battery receptacle accommodatedon the tool housing, the battery receptacle being adapted to receive abattery pack having a maximum voltage of at least 60 volts; and abrushless DC (BLDC) motor disposed within the tool housing, the motorincluding a stator assembly and a rotor assembly rotatably disposedwithin the stator assembly. In an embodiment, the power tool includes amotor control and power module disposed in close proximity to the motor,including a power switch circuit electrically coupled to the motor and afirst controller configured to control a switching operation of thepower switch circuit for supply of power from the battery pack to themotor. In an embodiment, the power tool further includes a batterymanagement control module disposed in close proximity to the batteryreceptacle, including a second controller distinct from the firstcontroller, the second controller configured to manage an operation ofthe battery pack.

In an embodiment, battery control wires are provided connecting thebattery receptacle to the battery management control module, and motordrive wires are provided connecting the motor control and power moduleto the motor.

In an embodiment, the battery management control module further includesa power supply regulator configured to output a power line having alower voltage than the battery pack to the first and second controllers.

In an embodiment, the motor control and power module comprises a firstprinted circuit board (PCB) on which the power switch circuit and thefirst controller are mounted, and the battery management control modulecomprises a second printed circuit board (PCB) on which the secondcontroller is mounted.

In an embodiment, the power tool further includes asubstantially-cylindrical motor housing including an open end forreceiving the stator assembly and a rear end, and a mounting bracket ator near the rear end of the motor housing, where the mounting bracketsupports the motor control and power module such that the first PCB issubstantially parallel to the rear end of the motor housing.

In an embodiment, the battery management control module includes amodule housing longitudinally disposed along an outer surface of thestator such that the second PCB is substantially parallel to an axis ofthe motor.

In an embodiment, the mounting bracket includes a substantiallycylindrical portion arranged to mate around a circumferential portion ofthe motor housing at or near the rear end of the motor housing, a planarportion extending radially outwardly from the cylindrical portion, andmount posts located around the planar portion.

In an embodiment, the power tool further includes a rear coverconfigured to mate with the mount posts to support the motor control andpower module proximate the rear end of the motor housing.

In an embodiment, the power switch circuit includes a plurality ofInsulated-Gate Bipolar Transistors (IGBTs) configured as a three-phasebridge driver circuit, and at least one heat sink mounted on the firstPCB in thermal communication with the IGBTs, the rear cover and themounting bracket together defining at least one peripheral openingadjacent the motor control and power module to allow passage of air tothe heat sink.

In an embodiment, the motor further includes a fan rotatably coupled tothe rotor assembly, and the rear end of the motor housing includes atleast one opening to provide fluid communication between the motor fanand the motor control and power module.

According to another aspect of the invention, a power tool is providedincluding a tool housing; a brushless DC (BLDC) motor disposed withinthe tool housing, the motor including a stator assembly and a rotorassembly rotatably disposed within the stator assembly; and asubstantially-cylindrical motor housing having an open end for receivingthe stator assembly and a rear end. In an embodiment, the power toolfurther includes a motor control and power module disposed in closeproximity to the motor, the motor control and power module comprising aprinted circuit board (PCB), a power switch circuit electrically mountedon the PCB and coupled to the motor, and a controller also mounted onthe PCB and configured to control a switching operation of the powerswitch circuit for supply of power from a power source to the motor. Inan embodiment, a mounting bracket is provided at or near the rear end ofthe motor housing, the mounting bracket supporting the motor control andpower module such that the PCB is disposed substantially parallel to therear end of the motor housing.

In an embodiment, the mounting bracket includes a substantiallycylindrical portion arranged to mate around a circumferential portion ofthe motor housing at or near the rear end of the motor housing.

In an embodiment, the motor housing includes guide rails on its outersurface, and the cylindrical portion comprises legs that slidingly matewith the guide rails of the motor housing.

In an embodiment, the mounting bracket further includes a planar portionextending radially outwardly from the cylindrical portion, and mountposts located around the planar portion. In an embodiment, mount postsextend outwardly at an angle from the planar portion.

In an embodiment, the power tool further includes a rear coverconfigured to mate with the plurality of mount posts to support themotor control and power module proximate the rear end of the motorhousing.

In an embodiment, the power switch circuit includes a plurality ofInsulated-Gate Bipolar Transistors (IGBTs) configured as a three-phasebridge driver circuit, and at least one heat sink mounted on the PCB inthermal communication with the IGBTs, the rear cover and the mountingbracket together defining at least one peripheral opening adjacent themotor control and power module to allow passage of air to the heat sink.

In an embodiment, two heat sinks are provided, each heat sink includinga curved surface that substantially covers a side surface and a topsurface of the corresponding IGBTs, and fins projecting outwardly fromthe curved surface.

In an embodiment, the motor further comprises a fan rotatably coupled tothe rotor assembly, and the rear end of the motor housing includes atleast one opening to provide fluid communication between the motor fanand the motor control and power module.

In an embodiment, the mounting bracket comprises wire routing andretention features on an inner portion thereof for receiving motor wiresfrom the motor.

According to another aspect of the invention, a power tool is providedincluding a tool housing and a brushless DC (BLDC) motor disposed withinthe tool housing, where the motor includes a stator assembly, and arotor assembly rotatably disposed within the stator assembly. In anembodiment, the rotor assembly includes a rotor shaft, a rotorlamination stack mounted on the rotor shaft to rotate therewith, a rearbearing arranged at a distal end of the rotor shaft, and a sense magnetdisposed between the rear bearing and the rotor lamination stack torotate with the rotor lamination stack. In an embodiment, the power toolfurther includes a substantially-cylindrical motor housing having anopen end for receiving the stator assembly and a rear end, the motorhousing including a substantially-cylindrical bearing pocket formed inits rear end to receive the rear bearing of the motor therein, and aradially-extending slot formed at or near its rear end. In anembodiment, a positional sensor board is radially received within theslot, the positional sensor board having a curved inner edge shaped tobe positioned in contact with the bearing pocket, the positional sensorboard including positional sensors mounted around the curved inner edgeand facing the sense magnet. In an embodiment, the curved inner edge ofthe positional sensor board is on a corner portion thereof to give thepositional sensor board an asymmetric shape.

In an embodiment, a receiving axis of the slot is offset with respect toa center of the bearing pocket.

In an embodiment, the bearing pocket includes a cylindrically-shapedmember located outwardly from the rear end of the motor housing awayfrom the rotor assembly and supported via angular legs.

In an embodiment, the slot is formed as a recess in an outer surface ofthe rear end of the motor housing.

In an embodiment, the motor housing includes guides and retentionfeatures around the slot to racially receive and retain the positionalsensor board within the slot.

In an embodiment, the power tool further includes a bracket mounted ator near the rear end of the motor housing, the bracket including atleast one axial finger arranged to hold the positional sensor boardwithin the slot.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of this disclosure in any way.

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of this disclosure in any way.

FIG. 1 depicts an exemplary perspective view of a high-power power tool,according to an embodiment;

FIG. 2 depicts a simplified conceptual block diagram of a conventionalcontrol scheme for driving a motor within a DC power tool andcontrolling the operation of the power tool and the tool battery pack;

FIG. 3 depicts an exemplary conceptual block diagram of a control schemefor driving a motor within a DC power tool and controlling the operationof the power tool and the tool battery pack, according to an embodiment;

FIGS. 4 and 5 depict perspective views of the power tool of FIG. 1 withthe housing and battery receptacles partially removed to show power toolmotor, motor control and power module, and battery management controlmodule, according to an embodiment;

FIG. 6 depicts a perspective view of the control and power module andthe battery management control module, according to an embodiment;

FIGS. 7 and 8 depict perspective views of a motor assembly including abrushless DC motor and the motor control and power module mountedthereto, according to an embodiment;

FIG. 9 depicts a partially exploded view of the motor assembly with thecontrol and power module spaced from the motor, according to anembodiment;

FIG. 10 depicts a fully exploded view of the motor assembly, accordingto an embodiment;

FIGS. 11 and 12 depict exploded perspective views of the motor controland power module, according to an embodiment;

FIG. 13 depicts a perspective view of a mounting bracket, according toan embodiment;

FIG. 14 depicts a rear axial view of the mounting bracket mounted on themotor housing, according to an embodiment;

FIG. 15 depicts a perspective view of the battery management controlmodule added to the motor assembly of FIG. 7;

FIG. 16 depicts a partial perspective view of the tool housing receivingthe motor assembly and battery management control module therein;

FIG. 17 depicts a block diagram for the battery management controlmodule and the motor control and power module for the power tool,according to an embodiment;

FIGS. 18 and 19 depict rear perspective views of the motor housing witha positional sensor board in unassembled and assembled statesrespectively, according to an embodiment;

FIGS. 20 and 21 depict front perspective views of the motor housing withthe positional sensor board in unassembled and assembled statesrespectively, according to an embodiment; and

FIG. 22 depicts a perspective view of the motor housing with analternative bracket, according to an embodiment.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Reference is initially made to application Ser. No. 14/715,258 filed May18, 2015, which is incorporated herein by reference in its entirety, fordetailed description of a power tool system including high-power (i.e.60V or above) DC-only or AC/DC power tools having brushless DC (BLDC)motors. Reference is also made to application Ser. No. 14/057,003 filedOct. 13, 2013 (published as US. Pub. No. 2015/0111480), for detaileddescription of an exemplary AC powered power tool having a BLDC motor.This disclosure describes a motor and power module assembly that may beutilized in various high-power AC-only, DC-only, or AC/DC power toolshaving BLDC motors. Examples of such tools include, but are not limitedto, hammer drills, concrete nailers, miter saws, grinders, etc.

FIG. 1 depicts an exemplary high-power power tool, in this case a mitersaw 10, according to an embodiment. In an embodiment, miter saw 10 has agenerally circular base 12 with an attached fence 14, which basesupports a rotatable table 16 that is rotatably adjustable for settingthe miter angle of the work piece placed on the table 16. A saw bladeand motor assembly, indicated generally at 20, is operatively connectedto the table 16 by a linear guide mechanism, indicated generally at 22.The saw blade and motor assembly 20 includes a tool housing 24 housingan electric motor that is operatively connected through a belt and gearmechanism, not shown but located within housing portion 26 that drives asaw blade 28. A handle 30 enables an operator to move the blade andmotor assembly 20 into and out of engagement with a work piece that maybe placed on the table 16 adjacent the fence 14.

The miter saw as illustrated in FIG. 1 is illustrative and the teachingsof this disclosure may apply to any miter saw, or any other high-powerpower tool. For more details about an exemplary miter saw, reference ismade to U.S. Pat. No. 8,631,734, which is incorporated herein byreference in its entirety.

In an embodiment, the power tool 10 of the present disclosure mayinclude one or more battery receptacles 40. Battery receptacles 40 mayreceive two battery packs (e.g., two 60V max battery packs, or two20/60V max battery packs configured in their 60V max configuration) andconnect the two battery packs in series for a total of 120VDC.Alternatively, the battery receptacle may be adapted to receive anadaptor pack that is coupled to an AC power source and provides ACpower, through the battery receptacle 40 terminals, to the power tool10. Details of a high-power DC, or a high-power AC/DC power tool system,including the battery pack and adaptor configurations, is described inPCT Application Publication No. WO 2015/179318, which is incorporatedherein by reference in its entirety.

FIG. 2 depicts a simplified conceptual block diagram of a conventionalcontrol scheme for driving a motor within a DC power tool andcontrolling the operation of the power tool and the tool battery pack.In this diagram, a single control and power module 38 for management ofthe battery and power tool is provided. This module 38 is located at alocation between the battery receptacle(s) and the motor, and includes amicro-controller that handles all aspects of the tool and batterymanagement, including, but not limited to, monitoring and managing thetool and battery voltage, current, temperature, and other parameters.For example, the micro-controller receives battery control wires 131(voltage and temperature sense signals) from the battery pack(s). In theevent the voltage of the battery cells is below a certain voltagethreshold, or if the battery temperature is above a certain temperaturethreshold, the microcontroller shuts down power from the batterypack(s). The micro-controller also communicates with the motor via motorcontrol wires 133, including motor positional signals (e.g., Hallsignals) received by the micro-controller from the motor. Themicro-controller accordingly controls the supply electric power viathree motor drive wires 135 corresponding to the three phases of themotor. The micro-controller controls the motor commutation via a seriesof power switches within the module 38, as described later in detail.

In large battery-operated power tools such as miter saws, particularlythose that require high voltage power lines of, for example, 120V or230V voltage to supply power from the battery receptacle(s) to themotor, long battery control wires 131 and motor control wires 133between the control and power module 38, the battery pack(s), and themotor create significant electromagnetic noise. This noise often causeinaccurate reading of the motor positional signals and the battery sensesignals by the micro-controller.

According to an embodiment of the invention, in order to reduceelectromagnetic noise in such power tools, two separate control modulesare provided, as depicted in the simplified block diagram of FIG. 3. Inthis embodiment, a battery management control module 300 is provided inclose proximity to the tool battery receptacle 40. All the batteryvoltage and sense signals 130 are provided directly from the batteryreceptacle 40 to the battery management control module 300. Moreover, inan embodiment, motor control and power module 116 is provided in closeproximity to the motor 110. As discussed below, this module 116 may besecured via a mounting bracket to the end of the motor 110. All motorcontrol wires 133 and motor drive wires 135 arranged between the motorcontrol and power module 116 and the motor 110 are comparatively short.The two modules 116 and 300 communicate via a series of low-voltagesignals 136. In this embodiment, the length of the motor control wires133 and battery control wires 131 is significantly decreased. Thisreduces the amount of electromagnetic noise on the motor control wires133 and battery control wires 131, allowing the motor control and powermodule 116 and battery management control module 300 to receive motorand battery management signals more accurately.

FIGS. 4 and 5 depict two perspective views of tool 10, with the toolhousing 24 and battery receptacle 40 removed, in an embodiment. As shownin these figures, the motor control and power module 116 is secured tothe end of the motor 110 substantially parallel to the end of the motor110, whereas the battery management control module 300 is aligned nearthe battery receptacles 60 along an outer surface of the motor 110parallel to an axis of rotation of the motor 110.

Referring now to FIG. 6, a perspective view of the motor control andpower module 116 and the battery management control module 300 isprovided, according to an embodiment. As shown in this embodiment, motorcontrol and power module 116 includes a series of power switches 202such as insulated-gate bipolar transistors (IGBTs) configured as athree-phase bridge rectifier for driving the motor. The module 116further includes a heat sink 204 in close proximity to the powerswitches 202. The power switches 202 are mounted on a printed circuitboard (PCB) (herein covered by a layer of potting 206). A firstmicro-controller for controlling motor commutation is also mounted onthe PCB. Cover 220, together with mounting bracket 114 (see FIG. 2),encapsulate the PCB and the remaining components of motor control andpower module 116 at the end of the motor 110. The motor control andpower module 116 is described in greater detail later in thisdisclosure.

In an embodiment, control and power module 116 outputs motor drive wires135, which connect to the motor terminal via a female connector 262. Themodule 116 also receives positional (Hall) signals via signal wires 213connected to the motor hall sensors via another connector 211.

In an embodiment, the battery management control module 300 is coupledto the battery receptacle 40 to receive B+/B− power lines, in additionto battery voltage and temperature sense signals 131. The module 300includes a housing 301 that houses a PCB on which a secondmicro-controller for controlling battery and tool management is mounted.Module 300 is coupled to and communicates with motor control and powermodule 116 via signal wires 305, as discussed below. Module 300 alsocommunicates with additional tool components (e.g., tool LEDs) viaconnector 307.

In an embodiment, the battery B+ and B− power lines may be provided tothe motor control and power module 116 either directly from the batteryreceptacle 40, or from the battery management control module 300.

FIGS. 7 and 8 depict perspective front and back views of a motorassembly 100 including brushless DC motor 110 and motor control andpower module 116 assembled thereto, according to an embodiment.

FIG. 9 depicts a partially exploded view of the motor assembly 100,wherein control and power module 116 and mounting bracket 114 are shownat a distance from the motor 110.

FIG. 10 depicts an exploded view of the motor assembly 100, where motor110 components are also shown at a distance.

Referring to all FIGS. 7-10, the details of the motor 110 are discussedherein.

In an embodiment, motor 110 includes a motor housing 120, a mount 112attached to one end of the motor 110 for securely attaching the motor110 inside a power tool housing (not shown), a mounting bracket 114secured on the second end of the motor 110, and control and power module116 secured to the mounting bracket 114, as described later in detail.In an embodiment, motor 110 is a three-phase brushless DC (BLDC) motorincluding a stator assembly 130 and a rotor assembly 140 housed withinthe motor housing 120.

In an embodiment, rotor assembly 140 includes a rotor shaft 142, a rotorlamination stack 144 mounted on and rotatably attached to the rotorshaft 142, a rear bearing 146 arranged at a distal end of the rotorshaft to axially secure the rotor shaft 142 inside a bearing pocket (notshown) of the motor housing 120, a sense magnet ring 148 attached to anend of the rotor lamination stack 144, and fan 150 also mounted on androtatably attached to the rotor shaft 142.

In an embodiment, the rotor lamination stack 144 may include a series offlat laminations attached together via, for example, an interlockmechanical, an adhesive, an overmold, etc., that house or hold two ormore permanent magnets (PMs) therein. The permanent magnets may besurface mounted on the outer surface of the lamination stack 144 orhoused therein. The permanent magnets may be, for example, a set of fourPMs that magnetically engage with the stator assembly 140 duringoperation. Adjacent PMs have opposite polarities such that the four PMshave, for example, an N-S-N-S polar arrangement. The rotor shaft 142 issecurely fixed to the rotor lamination stack 144.

Rear bearing 146 provides longitudinal support for the rotor 140assembly. In an embodiment, fan 150 includes a series of blades 152extending circumferentially to generate air flow through the motorhousing 120 as the rotor shaft 142 rotates.

In an embodiment, stator assembly 130 includes a generally cylindricallamination stack 132 having center bore configured to receive the rotorassembly 140. Lamination stack 132 further includes a plurality ofstator teeth around which stator windings 134 are wound. In athree-phase BLDC, windings 134 are coupled in pairs to form three phasesof motor 110. Electric energy is supplied to phases of the motor 110 viathree input terminals 137 in a controlled fashion, causing the rotorlamination stack 144 to rotate inside the stator lamination stack 132.

In an embodiment, motor housing 120 includes an open end to receive thestator assembly 130 therein. A rear end of the motor housing 120includes slots (not shown) allowing input terminals 137 of the statorassembly 130 to project outside the rear end of the motor housing 120.Motor housing 120 further includes a bearing pocket (not shown) at itsrear end to receive the rear bearing 146, thus securing the rotorassembly 140 inside the stator assembly 130.

FIGS. 11 and 12 depict exploded perspective views of the motor controland power module 116 only, according to an embodiment. Details of themotor control and power module 116 are discussed herein with referenceto FIGS. 11 and 12, with continued reference to FIGS. 7-10.

In an embodiment, control and power module 116 includes a printedcircuit board (PCB) 200 having a series of power switches 202, i.e.,transistors, such as Field Effect Transistors (FETs) or Insulated-GateBipolar Transistors (IGBTs) mounted thereon. Power switches 202 may beconfigured, for example, as a three-phase bridge driver circuitincluding three high-side and three low-side power switches 202connected to drive the three phases of the motor 110. In an embodiment,the gates of the power switches 202 may be driven by a series of sixcontrol signals from a controller (e.g., a micro-controller or otherprogrammable module) located either within the power module 116 or at adifferent location within the power tool. Examples of such a circuit maybe found in US Patent Publication No. 2013/0342144, which isincorporated herein by reference in its entirety.

In an embodiment, circuit board 200 is electrically coupled to a powersource (e.g., a battery pack) via power lines (not shown) for supplyingelectric power to the power switches 202. Circuit board 200 is alsoelectrically coupled to input terminals 137 of the motor 110 to powerthe phases of the motor 110 via the power switches 202.

According to an embodiment, a power tool employing the motor assembly100 described herein is a high-power tool configured to receive a 60Vmax battery pack or a 60V/20V convertible battery pack configured in its60V high-voltage-rated state. Alternatively and/or additionally, thepower tool may be configured to receive a 120V max battery pack, two 60Vmax battery packs connected in series for a total of 120V max DC power,or two 60V/20V convertible battery pack configured in their 60Vhigh-voltage-rated state and connected in series for a total of 120V maxDC power. The power tool may additionally and/or alternatively becoupled to a 120V or 230V AC power supply.

The motor 110 is accordingly configured for a high-power applicationwith an appropriate stack length, winding sizes, and number of windingturns. Similarly, the power switches 202 are appropriately chosen inaccordance with the rated voltage of the power supply. Larger ratedvoltage power supply typically requires larger transistors that alsogenerate more heat. A pair of appropriately sized heat sinks 204 isaccordingly mounted on the circuit board 200 to carry heat away from thepower switches 202. Heat sinks 204, in an embodiment, may include acurved surface 212 that substantially covers a side surface and a topsurface of the power switches 202, and a plurality of fins 214projecting outwardly from the curved surface 212 to substantiallyincrease the total surface area of the heat sink 204.

In an embodiment, where the power tool is an AC/DC system (i.e., poweris supplied via an AC and/or DC power supply) or AC-only system (i.e.,power is supplied via only an AC power supply), power module 116 mayfurther include a bridge rectifier component 206 mounted on the circuitboard 200. The bridge rectifier component 206 may include four diodesarranged in a bridge to convert negative half cycles of the AC waveformto positive half cycles. In an embodiment, power module 116 may furtherinclude an additional heat sink 208 mounted on the circuit board 200adjacent the bridge rectifier component 206 to carry heat away from thediodes. In an embodiment, power module 116 may further include one ormore DC bus capacitors 210 (in this case three capacitors 210 connectedin series) mounted on the circuit board 200 and electrically connectedacross the bridge rectifier component 206. For more details on circuitcomponents and connectivity of the power module 116, reference is madeto Ser. No. 14/715,258 filed May 18, 2015, which is incorporated hereinby reference in its entirety.

In an embodiment, control and power module 116 further includes a rearcover 220 designed to house the circuit board 200 therein. The rearcover 220 includes retaining features 222 designed to mate with and holdthe edges of the circuit board 200, and through-holes 224 arranged tomate with corresponding fastener receptacles described below.

Referring again to FIGS. 7-10, and further with reference to FIGS. 13and 14, mounting bracket 114 is described herein, according to anembodiment of the invention.

FIG. 13 depicts a perspective view of the mounting bracket 114, alone,according to an embodiment.

FIG. 14 depicts a rear axial view of the mounting bracket 114 mounted onthe motor housing 120, according to an embodiment.

In an embodiment, mounting bracket 114 includes a substantiallycylindrical portion 230 facing the motor 110 arranged to mate around acircumferential portion of the motor housing 120 at its rear end. Thecylindrical portion 230 includes four legs 232 that mate with and slideover corresponding guide rails 122 on the motor housing 120. At distalends of the legs 232 are disposed four fastening receptacles 244 thatallow the mounting bracket 114 to be secured to the end of the motorhousing 120 via fasteners 246.

In an embodiment, extending opposite the motor 110, mounting bracket 114includes a planar portion 238 and four mount posts 236 extendingoutwardly from the planar portion 238. In an embodiment, mount posts 236may extend radially, i.e., at an angle with respect to the planarportion 238. In an embodiment, mount posts 236 are arranged around acircumference that has a larger diameter than a circumference of thelegs 232. Mount posts 236 include fastener receptacles 234 arranged tomate with through-holes 224 of the rear cover 220 of the control andpower module 116 to receive fasteners therethrough.

In an embodiment, disposed between adjacent mount posts 236 of themounting bracket 114 are axial walls 240 and/or openings 242 positionedto direct air flow through the control and power module 116.Specifically, by disposing openings 242 adjacent the heat sinks 204and/or 208, the mounting bracket 114, including the inner surface of thewall 240, planar portion 238, and cylindrical portion 230, act asbaffling elements to direct the air flow generated by the motor fan 150to enter through the control and power module 116, particularly in areasaround the heat sinks 204 and 208, prior to entering the motor 110through openings 243 in the rear end of the motor housing 120. Walls 240and openings 242 are sized appropriately according to the size of thenearest heat sink 204 or 208. In an embodiment, two opposing walls 240adjacent heat sinks 204 have a smaller length to provide a largeropening 242 as compared to wall 240 opposite heat sink 208. In thismanner, mounting bracket 114 directs air flow generated by the motor fan150 through the control and power module 116 to help carry heat awayfrom the heat sinks 204, 208, and therefore the power components on thecircuit board 200.

In an embodiment, mounting bracket 114 also provides wire routing andconnectivity features between the motor 110 and the control and powermodule 116. In an embodiment, motor wires 250 coming out of the inputterminals are routed through routing features 252 provided on a rearsurface of the planar portion 238 of the mounting bracket 114, and areguided to motor-side male connector 260 on the side of the mountingbracket 114. Male connector 260 is snap-fittingly secured to an outersurface of the cylindrical portion 230 of the mounting bracket 114 viaretaining features 254. The female connector 262 of motor control andpower module 116 is similarly secured to the outer surface of thecylindrical portion 230. Female connector 262 is coupled to powerswitches 202 of the motor control and power module 116 via motor drivewires 135 previously described. During the assembly processed, femaleconnector 262 of the control and power module 116 mates with maleconnector 260 of the input terminals 137 of the stator assembly 130 toestablish a connection between the control and power module 116 and themotor 110.

In an embodiment, mounting bracket 114 additionally or alternativelyincludes a pair of fingers 270 to hold a positional sensor board 280within a slot 272 of the motor housing 120, as described below indetail.

FIG. 15 depicts a perspective of the brushless DC motor 110 and powermodule assembly 100 described above, additional provided with batterymanagement control module 300, according to an embodiment. As seenherein, the battery management control module 300 is axially disposedalong an outer surface of the motor housing 120.

FIG. 16 depicts a partial perspective view of tool housing 24 receivingthe brushless DC motor 110 and the battery management control module 300therein, according to an embodiment. As seen herein, tool housing 24, apart of which is removed to expose the motor 110, the motor control andpower module 116, and the battery management control module 300,includes an axial pocket 25 for receiving the battery management controlmodule 300 therein in parallel to the motor housing 120.

FIG. 17 depicts an exemplary block circuit diagram for a two-controllersystem of the present disclosure, according to an embodiment.

In an embodiment, motor control and power module 116 includes a powerunit 320 and a control unit 330.

In an embodiment, power unit 320 may include a power switch circuit 322coupled between the power source B+/B− terminals and motor windings todrive BLDC motor 110. In an embodiment, power switch circuit 322 may bea three-phase bridge driver circuit including six controllablesemiconductor power switches 202 (e.g. FETs, BJTs, IGBTs, etc).

In an embodiment, control unit 330 may include a controller 332 and agate driver 334. In an embodiment, controller 332 is a programmabledevice (e.g., a micro-controller, micro-processor, etc.) arranged tocontrol a switching operation of the power devices in power switchingcircuit 322. In an embodiment, controller 332 handles all aspect ofmotor control, including, but not limited to, motor drive andcommutation control (including controlling the switching operation ofthe power switching circuit 322 to control motor speed, forward/reversedrive, phase current limit, start-up control, electronic braking, etc.),motor stall detection (e.g., when motor suddenly decelerates or motorcurrent rapidly rises), motor over-voltage detection and shutdowncontrol, motor or module over-temperature detection and shutdowncontrol, electronic clutching, and other control operations related tothe motor.

In an embodiment, controller 332 receives rotor rotational positionsignals from a set of position sensors 282 provided in close proximityto the motor rotor 140, specifically from the sense magnet ring 146, aswill be discussed later in detail. In an embodiment, position sensors282 may be Hall sensors. It should be noted, however, that other typesof positional sensors may be alternatively utilized. It should also benoted that controller 332 may be configured to calculate or detectrotational positional information relating to the motor 110 rotorwithout any positional sensors (in what is known in the art assensorless brushless motor control). Based on the rotor rotationalposition signals from the position sensors 382, controller 332 outputsdrive signals UH, VH, WH, UL, VL, and WL through the gate driver 334.Gate driver 334 is provided to output the voltage level needed to drivethe gates of the semiconductor switches 202 in order to control a PWMswitching operation of the power switch circuit 322.

In an embodiment, battery management control module 300 includes abattery controller 302 that is separate and distinct from the motorcontroller 332, a battery sense unit 304, a power supply regulator 306,and an input unit 308.

The power supply regulator 306 may include one or more voltageregulators to step down the power supply to a voltage level compatiblefor operating the two controllers 332 and 302 and/or the gate driver334. In an embodiment, power supply regulator 306 may include a buckconverter and/or a linear regulator to reduce the power voltage from thebattery receptacle 40 down to, for example, 15V for powering the gatedriver 334, and down to, for example, 3.3V for powering the controllers302 and 332.

In an embodiment, battery controller 302, similarly to motor controller232, is programmable device (e.g., a micro-controller, micro-processor,etc.) arranged to control various management aspects of the battery andthe power tool. In an embodiment, controller 302 detects when the toolis turned on or off power switch 340 and initiates and/or cuts offsupply of power to motor control and power module 116 accordingly. In anembodiment, battery controller accomplishes this by cutting off thesupply of power to the motor controller 332 and/or gate driver 234 fromthe power supply regulator 306. The battery controller 302 mayadditionally or alternatively receive forward/reverse or trigger on/offsignals from an input unit 308 coupled to a trigger switch. The batterycontroller 302 also receives sense signals of the battery packs viabattery sense unit 304, determines if the battery is experiencing afault condition (e.g., under-voltage, over-current, over-temperature,etc.), and shuts off the supply of power accordingly. In an embodiment,the two controllers 332 and 302 communicate via a serial communicationprotocol, e.g., Universal Asynchronous Receiver/Transmitter (UART). Inan embodiment, battery controller 302 additionally controls othercomponents such as LEDs 350 based on, for example, a state of charge ofthe battery 40.

The above-described embodiment allows for reduced overall wire length,minimizing wiring and routing cost and improving signal integrity ofanalog signals received by the controllers. Also, the size of the largerbus lines is substantially reduces, e.g., by 2 to 6 inches. Theseinclude battery control wires 131, which include a total of seven wiresfor battery voltage and temperature sensing of the two battery packs;motor control wires 133, which include five wires for hall sensors; andmotor drive wires 135, which include three high-current wires. Reducingthe size of these wires according to this design minimizes the noise onthe motor and battery signals, thus improving system reliability andaccuracy.

It is noted that while the circuit diagram of FIG. 17 is designed for apower tool that receives DC power, the principle teachings of thisdisclosure may similarly be applied to an AC/DC power tool capable ofreceiving AC or DC power, where the AC power is passed through arectifier circuit. Examples of such a system are described in PCTApplication Publication No. WO 2015/179318 filed May 18, 2015, which isincorporated herein by reference in its entirety.

The structure and assembly of positional sensor board 280 is describedherein, according to an embodiment of the invention.

Referring to FIGS. 18-21, which show perspective front and back view ofthe motor housing 120, without the stator assembly 130 or rotor assembly140 mounted therein, respectively depict positional sensor board 280disposed outside and inside the slots 272 of the motor housing 120,according to an embodiment. In an embodiment, slot 272 is locatedradially on the motor housing 120 at or near rear end 290 of the motorhousing 120. In the illustrated embodiment, the slot 272 is formedintegrally as a recessed surface on the rear end 290, though it must beunderstood that the slot 272 may be disposed on the outer surface 292 ofthe motor housing 120 at a short distance to the rear end 290.

In an embodiment, positional sensor board 280 includes a series of threepositional sensors (e.g., three Hall sensors) 282 on a surface thereoffacing the rotor assembly 140. In an embodiment, positional sensor board280 is received radially through the slot 272 such that positionalsensors 282 are exposed inside the motor housing 120 to the rotorassembly 140 sense magnet ring 148. In an embodiment, the motor housing120 includes guide and retention features 273 around the slot 272 toradially receive and retain the positional sensor board 280 within theslot 272. In an embodiment, positional sensor board 280 also includes aconnector 283 on a surface thereof opposite the positional sensors 282.

In an embodiment, positional sensor board 280 includes a curved inneredge 284 and the positional sensors 282 are arranged around the curvedinner edge. In an embodiment, curved inner edge 284 is on a cornerportion of the positional sensor board 280 to give the positional sensorboard 280 an asymmetric shape. In an embodiment, slot 272 is disposed inthe motor housing 120 offset with respect to a center of the motorhousing 120 such that a receiving axis of the slot 272 does notintersect the center of the bearing pocket 294 (i.e., axis of the motorshaft 142).

In an embodiment, bearing pocket 294 is located downstream from the rearend 290 of the motor housing 120 from the rotor assembly 140. In anembodiment, bearing pocket 294 is a cylindrically-shaped member thatprojects from the rear end 290 of the motor housing 120 and isadditionally supported via angular legs 296. In an embodiment, slot 272extends partially on the rear end 292 and partially on the outer surfaceof the bearing pocket 294.

In an embodiment, when positional sensor board 280 is received throughthe slot 272, its curved edge 284 comes to contact with an inner ring298 of the bearing pocket 294, and thus the positional sensors 282 arepositioned outside the inner ring 298 of the bearing pocket 294. Thisarrangement allows the positional sensors 282 to be disposed at closeaxial proximity to the sense magnet 148 of the rotor assembly 150 whenfully assembled. Furthermore, the curved edge 284 of the positionalsensor board 280 ensures that the positional sensor board 280 does notinterfere with the assembly of the rotor assembly 140 in the motorhousing 120. In particular, the curved edge 284 of the positional sensorboard 280 allows the rear bearing 146 to pass by the positional sensorboard 280 and be axially received into the bearing pocket 294.

While the positional sensor board 280 in the above-described includes acurved edge to be disposed round the inner ring 298 of the bearingpocket 294, positional sensor board 280 may alternatively be rectangularshaped such that, once received inside the slot 272, it axially overlapsthe bearing pocket 294. In this embodiment, during the assembly process,the positional sensor board 280 is inserted into the slot 272 after therotor assembly 140 is assembled into the motor housing 120 so that thepositional sensor board 280 does not interfere with insertion of therear bearing 146 into the bearing pocket 294.

In an embodiment, as briefly discussed above, mounting bracket 114includes a pair of fingers 270 to hold a positional sensor board 280within a slot 272 of the motor housing 120. Fingers 270 are spaced apartto allow access to connector 283 when fully assembled.

Referring now to FIG. 22, an alternative bracket 400 is describedherein. Bracket 400 is similar to mounting bracket 114, but does notprovide mounting support for a control and power module. Such a bracket400 may be utilized in power tools where the control and power circuitryis located at another part of the tool rather than the back of the motorhousing, or where the power module is secured on the back of the motordirectly to the tool housing. In an embodiment, bracket 400 includeslegs 402, cylindrical portion 404, and planar portion 406 similarly tomounting bracket 114 described above. Bracket 400 may house connectors(not shown) between the motor and the power module, as described above.Bracket 400 also includes fingers 408 disposed to hold the positionalsensor board 280 in place, as described above.

Some of the techniques described herein may be implemented by one ormore computer programs executed by one or more processors residing, forexample on a power tool. The computer programs includeprocessor-executable instructions that are stored on a non-transitorytangible computer readable medium. The computer programs may alsoinclude stored data. Non-limiting examples of the non-transitorytangible computer readable medium are nonvolatile memory, magneticstorage, and optical storage.

Some portions of the above description present the techniques describedherein in terms of algorithms and symbolic representations of operationson information. These algorithmic descriptions and representations arethe means used by those skilled in the data processing arts to mosteffectively convey the substance of their work to others skilled in theart. These operations, while described functionally or logically, areunderstood to be implemented by computer programs. Furthermore, it hasalso proven convenient at times to refer to these arrangements ofoperations as modules or by functional names, without loss ofgenerality.

Certain aspects of the described techniques include process steps andinstructions described herein in the form of an algorithm. It should benoted that the described process steps and instructions could beembodied in software, firmware or hardware, and when embodied insoftware, could be downloaded to reside on and be operated fromdifferent platforms used by real time network operating systems.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises,” “comprising,” “including,” and“having,” are inclusive and therefore specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The method steps, processes, and operations described hereinare not to be construed as necessarily requiring their performance inthe particular order discussed or illustrated, unless specificallyidentified as an order of performance. It is also to be understood thatadditional or alternative steps may be employed.

The invention claimed is:
 1. A power tool comprising: a tool housing; atleast one battery receptacle accommodated on the tool housing, thebattery receptacle being adapted to receive a battery pack having amaximum voltage of at least 60 volts; a brushless DC (BLDC) motordisposed within the tool housing, the motor including a stator assemblyand a rotor assembly rotatably disposed within the stator assembly; amotor control and power module comprising: a first printed circuit board(PCB) disposed within the tool housing close to the motor, a powerswitch circuit electrically including a plurality of semiconductor powerswitches coupled to the motor, a gate driver circuit arranged to outputdrive signals to the plurality of semiconductor power switches, and afirst controller being a programmable device mounted on the first PCB,the first controller being configured to output a plurality of controlsignals to the gate driver circuit to drive the plurality ofsemiconductor switches to control a supply of power from the batterypack to the motor; and a battery management control module comprising: asecond printed circuit board (PCB) disposed within the tool housingclose to the battery receptacle at a distance from the first PCB, and asecond controller distinct from the first controller being aprogrammable device mounted on the second PCB, the second controllerconfigured to receive a signal related to at least one of a temperatureor voltage of the battery pack from the battery receptacle and manage anoperation of the battery pack accordingly.
 2. The power tool of claim 1,comprising a plurality of battery control wires connecting the batteryreceptacle to the battery management control module, and a plurality ofmotor drive wires connecting the motor control and power module to themotor.
 3. The power tool of claim 1, wherein the battery managementcontrol module further includes a power supply regulator configured tooutput a power line having a lower voltage than the battery pack to thefirst and second controllers.
 4. The power tool of claim 1, wherein thepower switch circuit and the gate driver circuit are mounted on thefirst PCB.
 5. The power tool of claim 4, comprising asubstantially-cylindrical motor housing having an open end for receivingthe stator assembly and a rear end, and a mounting bracket at or nearthe rear end of the motor housing, the mounting bracket supporting themotor control and power module such that the first PCB is substantiallyparallel to the rear end of the motor housing.
 6. The power tool ofclaim 5, wherein the battery management control module comprises amodule housing longitudinally disposed along an outer surface of thestator such that the second PCB is substantially parallel to an axis ofthe motor.
 7. The power tool of claim 5, wherein the mounting bracketcomprises a substantially cylindrical portion arranged to mate around acircumferential portion of the motor housing at or close to the rear endof the motor housing, a planar portion extending radially outwardly fromthe cylindrical portion, and a plurality of mount posts located aroundthe planar portion.
 8. The power tool of claim 7, further comprising arear cover configured to mate with the plurality of mount posts tosupport the motor control and power module proximate the rear end of themotor housing.
 9. The power tool of claim 8, wherein the power switchcircuit comprises a plurality of Insulated-Gate Bipolar Transistors(IGBTs) configured as a three-phase bridge driver circuit, and at leastone heat sink mounted on the first PCB in thermal communication with theIGBTs, the rear cover and the mounting bracket together defining atleast one peripheral opening adjacent the motor control and power moduleto allow passage of air to the heat sink.
 10. The power tool of claim 9,wherein the motor further comprises a fan rotatably coupled to the rotorassembly, and the rear end of the motor housing comprises at least oneopening to provide fluid communication between the motor fan and themotor control and power module.